1. Field of the Invention
The present invention relates to passing routing information in a network under one party's administrative control that includes paths, such as layer 3 virtual private network paths, across a different network under a different party's administrative control.
2. Description of the Related Art
Networks of general purpose computer systems and specialized devices connected by external communication links are well known and widely used in commerce. The networks often include one or more network devices that facilitate the passage of information between the computer systems and devices. A network node is a network device or computer or specialized device connected by the communication links. An end node is a node that is configured to originate or terminate communications over the network. An intermediate network node facilitates the passage of data between end nodes.
Communications between nodes are typically effected by exchanging discrete packets of data. Information is exchanged within data packets according to one or more of many well known, new or still developing protocols. In this context, a protocol consists of a set of rules defining how the nodes interact with each other based on information sent over the communication links. A routing protocol is designed to provide information that is used by a routed protocol to determine which links to use at an intermediate network node to forward data packets across heterogeneous networks (called internetworks, including the Public Internet) that may use different physical media to form links between adjacent nodes or may be under different administrative control, or both. An intermediate network node that forwards data packets based on routing protocol information is called a router.
Network service providers (called “providers” hereinafter) offer wide area networks and sophisticated services that can allow geographically dispersed networks of one entity, called a “customer” hereinafter, to communicate. Example services include internetwork virtual private networks (VPNs). In these services, routing information at one customer site is converted from the internal routing protocol used by the customer at all sites to an external routing protocol used among service providers, and then back to the internal routing protocol at a second customer site. It would be useful if a node at the second customer site could check that the internal routing protocol information received is valid.
An autonomous system refers to a collection of nodes and routers under administrative control of a single entity. An autonomous system uses an internal routing protocol for passing routing information used within the autonomous system and an external routing protocol to pass routing information between different autonomous systems. Currently, some external routing protocols provide methods to check certain aspects of validity of routing information that has passed across several different autonomous systems. However, an autonomous system, such as a customer network, with multiple sites that rely on an external routing protocol to span one or more other autonomous systems to send routing information from a local site to a remote site is not currently able to check whether error, inattention or malfeasance in an intervening autonomous system has led to incorrect or misleading routing information being received at the remote site.